1. Field of the Invention
The present invention relates generally to an apparatus for recording and/or reproducing an information signal, and, more particularly, is directed to such apparatus in which differently modulated information signals recorded in a recording medium are identified for reproducing them appropriately.
2. Description of the Prior Art
A video tape recorder (VTR) for recording and/or reproducing a color video signal and an audio signal has been proposed wherein the video signal is separated into a low frequency-converted chrominance signal and a frequency modulated luminance signal to be recorded on, and reproduced from a magnetic tape, while the audio signal is frequency modulated to be recorded on the magnetic tape and reproduced therefrom. In such a VTR, for example, a left channel signal and a right channel signal included in a stereo audio signal frequency modulate two carrier waves having frequencies different from each other to provide a left audio frequency modulated signal (L-AFM signal) and a right audio frequency modulated signal (R-AFM signal). The frequency bands of these L-AFM and R-AFM signals are situated between the frequency-converted chrominance signal frequency band and the frequency modulated luminance signal frequency band. For example, as shown in FIG. 4, the carrier frequencies of the L-AFM and the R-AFM signals may be 1.3 MHz and 1.7 MHz, respectively.
Another type of VTR is well known in which an audio signal is converted into pulse code modulated (PCM) digital data to be recorded on the magnetic tape, and the digital audio signal is reproduced prior to being digital/analog converted to an analog audio signal in order to improve tone quality. In this type of VTR, the PCM digital data is modulated according to quadriphase shift keying (QPSK) so as to obtain a QPSK modulated signal. The frequency band of such QPSK modulated signal is also provided between the frequency converted chrominance signal frequency band and the frequency modulated luminance signal frequency band, as shown in FIG. 4. In such case, the central frequency of the QPSK modulated signal may be 2 MHz. These audio frequency modulated signals (AFM) including a left AFM signal and a right AFM signal, or the QPSK modulated audio signal are recorded by rotary heads independent of the rotary heads used for recording video signals on a track area of the magnetic tape common to that used for the video signals. The video signals are recorded in a surface layer of the magnetic tape, while the QPSK modulated signals, or the AFM signals, are recorded in a deeper layer of the magnetic tape.
In order to reproduce such signals recorded at different levels in the magnetic coating on the tape, independent rotary video signal heads and rotary audio signal heads are provided to reproduce the video signals and the AFM or QPSK modulated signals, respectively. The reproduced video signals are supplied to a video signal reproducing system provided in the VTR, while the reproduced AFM or QPSK modulated signals are supplied to an audio signal reproducing system.
However, existing VTRs including an AFM signal reproducing system and existing VTRs including a QPSK modulated signal reproducing system are independent of each other. Thus, information signals including AFM signals and QPSK modulated signals cannot be reproduced by a single existing VTR. Further, users cannot readily discriminate between a magnetic tape in which AFM signals are recorded and a magnetic tape in which QPSK modulated signals are recorded. This causes great inconvenience in determining the type of VTR to be used for reproducing a magnetic tape recorded with video signals and AFM or QPSK modulated signals.